Dresser structures

ABSTRACT

Rotary dresser structures are described with specific reference to novel characteristics for dressing cup-shaped grinding wheels of the type which are useful for grinding teeth in face couplings. The dressing structures include a pair of rotary dressers for shaping and dressing side surfaces of the cup-shaped grinding wheel together with a third rotary dresser which dresses an annular end of the grinding wheel. The dresser structures which will be described are especially useful for precision dressing and for grooving grinding wheels which are to be used in high heat formation grinding operations.

United States Patent Inventors Thomas A. Deprez; 7%

Alvin W. Snook, both of Rochester, N.Y.

Mar. 3, 1969 Aug. 10, 197 1 The Gleason Works Rochester, N.Y.

Appl. No. Filed Patented Assignee DRESSER STRUCTURES 17 Claims, 22Drawing Figs.

US. Cl.

lut- CL.

Field of Search References Cited UNlT ED STATES PATENTS 7/1926 Slade1,689,565 10/1928 Trbojevich 2,360,127 10/1944 Harley PrimaryExaminerl-larold D. Whitehead Auorney-Cushman, Darby and CushmanABSTRACT: Rotary dresser structures are described with specificreference to novel characteristics for dressing cupshaped grindingwheels of the type which are useful for grinding teeth in facecouplings. The dressing structures include a pair of rotary dressers forshaping and dressing side surfaces of the cup-shaped grinding wheeltogether with a third rotary dresser which dresses an annular end of thegrinding wheel. The dresser structures which will be described areespecially useful for precision dressing and for grooving grindingwheels which are to be used in high heat formation grinding operations.

PATENTEUAUBIOISYI 3.598.100

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sum 15 0F 15 I INVENTORS 7% 0/445 fl. Dzpmez ATTORNEYS DRESSERSTRUCTURES BACKGROUND AND BRIEF DESCRIPTION OF INVENTION This inventionrelates to improvements in means for dressing grinding wheels, and inparticular the invention provides for rotary dressers havingcapabilities of precisely controlling contour and length of a cup-shapedgrinding wheel. The rotary dressers include shaped heads having abrasivesurfaces which are preferably formed by cementing diamond particles ontothe work-engaging surfaces, and the rotary dressers are provided withmounting and adjustment means for care fully controlling contact of thedressers with a grinding wheel during periodic dressing operations ofthe grinding wheel. In addition, an assembly of dressers is provided forpresenting a pair of dressers to opposite side surfaces of a cup-shapedgrinding wheel, and a third-dresser makes contact with an an- 7 nularedge of the grinding wheel. The three dressers are related to oneanother in such a way that the grinding wheel can be grooved on itssides and its annular end to improve its grindingcharacteristics when itis being used in high heat formation operations with a coolant.

It is known in the art of dressing grinding wheels and other members toprovide for single point diamond dresser structures which can controlthe: profile of a cup-shaped grinding wheel member. In fact, singlepoint dresser structures of the type shown'in US Pat. No. 2,409,240 havebecome almost the only means ofdressing certain forms of grinding wheelsin certain gear cutting operations. However, it is also known to providedresser structures in the. form of rotary dressers which can contact agrinding wheel to shape the wheel in accordance with rotating heads ofsuch dressers. Rotary dressers have been designed and constructed toprovide rotating abrasive surfaces which can contact and shape members,and it is known to form the abrasive surfaces of a rotary dresser bycementing or setting small particle diamonds onto the surfaciwhich mustengage a grinding wheel or other member;-

The present invention offers mounting and adjusting structures forrotary dressers which are especially adapted for precisely dressingcup-shaped grinding wheels of the type that may be used in grindingteethon. face gears and couplings. A typical machine and method ofoperation for such grinding is disclosed in my copending applicationentitled, Apparatus and Method for Grinding Toothed Face Members," asfiled even date herewith, by the assignee ofthis application.

In accordance with the present invention, very stable and preciselypositionable support structures are provided for three separate dressingunits. Two of the dressing units function as a pair of dressers whichsimultaneously contact opposite annular sides of a cup-shapedg'rinding'wheel, and the third dresser unit may be brought intosimultaneous engagement with an annular end surface of the grindingwheel. The mounting and support arrangements which are provided by thisinvention assure extremely precise and stable dressing operations whichcan be set and adjusted for the type of geometric accuracy and surfacefinish which are required for periodic dressing of cup-shaped grindingwheels useu in gear cutting operations. As is well-known, rotarydressers present special problems of deflection and vibration, ascompared to the more commonlyused single point dressers, however, thestructures of the present invention overcome problems which are normallyexpected'from rotary dresser usage. By utilizing rotary dressers, withthe precision arrangements offered by this invention, it is-possible todress a grinding wheel at a much higher rate of speed than would be thecase with single point dressers, and also, unusual surface finishes andconfigurations can be obtained for the first time..ln the specific usefor which the present invention is intended, as described in the abovementioned copending application, it has been found that a groovedconfiguration can be placed on a grinding wheel to improve its coolingcharacteristics while it is being used in high heat formation grindingoperations. Such operations may speed grinding, the result of removingrelatively large amounts of material from large workpieces, or grindingexotic materials of extreme hardness, but whatever the reason, it isdesirable to maintain the grinding wheel in a cool and safe conditionwhile the grinding operation is taking place. By dressing the grindingwheel with a grooved configuration, it is possible'to move a greaterquantity of coolant liquid into the grinding zone while the grindingwheel is engaging a workpiece. The rotary dresser structures of thisinvention can be used to automatically effect such a groovedconfiguration on a cup-shaped grinding wheel while simultaneouslydressing remaining surfaces of the grinding wheel to very precisetolerances and shapes.

' With three separate dresser units related to one another as providedby the present invention, it is possible to control the effective lengthof a cup-shaped grinding wheel independently of controlling the precisecontour of the grinding wheel. In addition, the three dresser units ofthis invention can be adapted for either rough or finish dressing of agrinding wheel, and repair and replacement of dressing heads can beaccomplished with a minimum of shutdown time for a grinding machine andwith assurance of a prescribed contour or adjustment being repeated witha replacement unit.

These and other advantages of the present invention will become moreapparent in the detailed description which follows, and in thatdescription reference will be made to the accompanying drawings asbriefly described below:

BRIEF DESCRIPTION OF DRAWINGS FIG. I is a front elevational view of agrinding machine of a type for which the dresser structures of thisinvention are especially useful;

FIG. 2 is a front elevational schematic view showing basic componentsofa pair ofdresser units ofthis invention;

FIG. 3 is a top plan view of what is shown in FIG. 2 together with aview of a third dresser unit of this invention;

FIG. 4 is a view of FIG. 2, as seen from line 4-4 of FIG. 2;

FIG. 5 is a front perspective view of three dresser units of thisinvention, as mounted on the machine shown in FIG. 1;

FIG. 6 is a rear perspective view of what is shown in FIG. 5;

FIG. 7 is a partially exploded perspective view of the first and seconddresser units shown in FIG. 5 as seen from the'bottom of the assembly;

FIG. 8 is a further exploded view of'the assembly shown in FIG. 7;

FIG. 9 is a top plan view showing details of a pair of dresser units,and adjusting means therefor, in a detailed embodiment of thisinvention;

FIG. 10 is a side elevational view of the embodiment shown in FIG. 9',

FIG. 11 is an end view, partially in section, as seen on line 11-11 ofFIG. 9;

FIG. 12 is an end view as seen on line 12-12 of FIG. 11;

FIG. 13 is an end view, partially in section, as seen on line 13-13ofFIG. 11;

FIG. 14 is a perspective view, partially exploded, of a third dresserunit in accordance with this invention;

FIG. 15 is a perspective, taken at a different angle than the view ofFIG. 14, showing exploded details of the third dresser unit;

FIG. 16 is a top plan view, partially in section, showing a thirddresser unit in a detailed embodiment thereof;

FIG. 17 is an end view of the embodiment of FIG. 16', as seen on line17-17 ofFIG. 16',

FIG. 18 is a sectional view of a detail of construction of the thirddresser unit;

FIG. 19 is a sectional view of a detail of construction of the thirddresser unit;

FIG. 20 is a sectional view of a detail of construction of the FIG. 22is a perspective view of an outside surface portion of a cup-shapedgrinding wheel which has been dressed and grooved with the apparatusofthis invention.

DETAILED DESCRIPTION OF INVENTION As mentioned above, this inventionrelates to improvements in structures for dressing grinding wheels, andthe improvements are especially concerned with dressing cup-shapedgrinding wheels of the type used for grinding toothed face members orpinions. The improvements of this invention provide a capability forautomatically dressing a grinding wheel at periodic intervals duringgrinding operations, and the dressing functions are carried out byrotary dressers which have capabilities of precisely dressing arequisite profile on a grinding wheel while simultaneously dressinggrooves into the grinding wheel if desired.

' Cup-shaped grinding wheels have been used for a number of grindingoperations for producing toothed face members and other gear members. Ina typical grinding operation, it has been the practice to oscillate thegrinding wheel into and out of actual contact with a workpiece so that acoolant can be introduced into the grinding area to reduce heat andprevent burning of the workpiece and deterioration of the grindingwheel. Prior practice has also provided for a periodic dressing of thegrinding wheel, usually with three single point dressing arms whichshape the sidewalls and annular end of the cupshaped grinding wheel.However, single point dressers, consisting of single diamond pointsmounted for dressing engagement with a grinding wheel, have certainlimitations in use because they require frequent adjustment tocompensate for wear on the diamond point which is initially presented toa grinding wheel. Present day technology requires the grinding ofrelatively large workpieces and of workpieces which are made fromespecially hard metals, such as titanium, and these grinding operationsproduce relatively high levels of heat during actual engagement of thegrinding wheel with the workpiece. In fact, the heat problem has becomeso great that it has become virtually impossible in certain grindingoperations to oscillate a grinding wheel rapidly enough to maintaincoolant in the grinding zone. A solution to this type of grindingproblem is described in the above mentioned copending application withreference to a method for forming grooves or undulations into thesidewalls and the annular end of a grinding wheel so that coolant can beintroduced into the grinding not while the grinding wheel is maintainedin actual grinding con tact with a workpiece. However, the use of agrooved grinding wheel has created special problems of how to dress such2 grinding wheel periodically during grinding operations so as I:

maintain a precise profile on the wheel while simultaneousl maintaininggrooves on both sidewalls and the annular end of the wheel. In order tomeet the needs of grinding techniques which utilize grooved grindingwheels, the present invention provides for dresser structures havingcapabilities of automatically and simultaneously dressing the entiregrinding profile of a cup-shaped wheel while, at the same time, dressinggrooves into the sidewalls and annular end of the wheel, if desired.However, the present invention is also very useful for dressingoperations which do not involve grooving ofa grinding wheel.

In accordance with the present invention, three separate rotary dresserunits are mounted in specific relationships to provide dressingfunctions which will maintain the profile of a grinding wheel and whichmay be used to maintain grooves in a grinding wheel. Unlike prior artuses of single point dressers, the present invention utilizes rotarydresser units having shaped heads which are preferably covered withdiamond pa. ticles. The shaped heads are rotated at relatively highspeeds relative to a rotating grinding wheel, and the rotation of theshaped heads can be reversed to effect changes in surface finish of agrinding wheel. In addition, the invention provides for a number ofadjustment features for two of the dresser units so that the same pairof units can be utilized for dressing the sidewalls of grinding wheelshaving different characteristics of size, pressure angle, and pointwidth. With the adjustment features which are provided by thisinvention, an identical pair of grinding wheels can be used for avariety of dressing operations, and also, the same pair of dresser unitsmay be used for dressing a grinding wheel for either convex or concavegrinding in the case of manufacturing toothed face members.

FIG. 1 is a schematic illustration, in elevation, of a typical machinewhich may utilize the dresser structures of this invention. The machinewhich is illustrated is described in greater detail in the abovementioned copending application, but generally, the machine is of a typewhich can grind curved toothed slots into a face ring of a couplingmember. However, it can be appreciated that the dresser structures ofthis invention can also be used in other grinding machines which utilizecup-shaped, or even disc shaped grinders, and which require periodicdressing of such grinders. The illustrated machine includes a cup-shapedgrinding wheel mounted in a housing 102 for rotation and reciprocationwithin the housing. Means are provided for rotating the grinding wheelduring dressing of the wheel and also during actual engagement with aworkpiece 104, and any suitable means may be included for oscillatingthe grinding wheel up and down on its vertical axis of rotation, asviewed in FIG; 1. Detailed descriptions of means for oscillating androtating the grinding wheel 100 are included in the above-mentionedapplication, and such means include motor means and control devices fordictating a sequence of movements to the grinding wheel, as may berequired for any particular grinding operation. FlG. 1 shows an assembly106 of dresser structures mounted on the machine so as to be movablefrom inoperative to operative positions for dressing the grinding wheel100. The dresser structure assembly 106 may be pivotally pinned at 108to a portion of the machine housing, and a hydraulic ram may beinterconnected between a portion of the machine and the dresser assembly106 to move the dresser assembly from the inoperative position (which isillustrated) to a dressing position (shown by dashed lines in FIG. 1).Any suitable control means may be provided for actuating the hydraulicram 110 at periodic intervals to place the dresser assembly 106 in aposition to receive the cup-shaped grinding wheel 100. When the dresserassembly is in a dressing position, the cup-shaped grinding wheel, whichopens downwardly in the illustrated embodiment, is moved downwardly onits vertical axis of rotation so as to engage separate dresser units ofthe dresser assembly.

Referring to FIGS. 2 and 3, it can be seen that the dresser assembly 106includes three separate rotary dresser units which are mounted inpositions for dressing the inner and outer sidewalls and the annular endof a cup-shaped grinding wheel. A first rotary dresser unit 112 contactsan inside sidewall portion 113 of the grinding wheel 100, and a secondrotary dresser unit 114 contacts and outside sidewall portion 115 of thegrinding wheel. As shown in FIG. 3, a third rotary dresser unit 116 ispositioned to contact the downwardly depending annular edge of thegrinding wheel 100. Thus, the three dresser units may be considered toinclude a pair of units 112 and 114 which cooperate to simultaneouslydress both inner and outer sidewalls of a cup-shaped grinding wheeltogether with a third dresser unit 116 which contacts and dresses theannular end of the grinding wheel. Of course, it is to be understoodthat the orientation of the dresser units and of the grinding wheel maybe changed from what is shown in FIG. 1 inasmuch as some grindingmachines mount cupshaped grinding wheels on horizontally disposed axesof rotation. Also, it can be appreciated that FIGS. 2 and 3 illustratethe dresser units in positions for actually dressing a grinding wheel,and when a dressing operation is completed, the entire assembly 106 ofdresser units is moved outof the way of the grinding wheel (as shown inFIG. 1) so that the grinding wheel can be brought into grindingengagement with the workpiece 104. In a typical operation, grinding iscarried on for a period of time before the grinding wheel is withdrawnfor periodic dressing, and the frequency of dressing depends largelyupon the type of grinding operation which is being carried out and theamount of deterioration of the grinding wheel which may exist for theparticular grinding operation.

FIGS. 2 through 4 illustrate the three dresser units of the presentinvention in a schematic form so as to emphasize basic components andadjustment features which are provided for the entire assembly FIGS. 5through illustrate the same three types ofdresser units in greaterdetail and with reference to a specific embodiment.

Referring to FIGS. 2 through 4, each of the three dresser units 112,114, and 116 comprises a rotary dresser unit having a shaped head whichcontacts a cup-shaped grinding wheel for dressing operations. The-shapedhead portion of each rotary dresser is preferably surfaced with diamondparticles in accordance with known techniques, and typical knownconstructions provide for a cementing or setting ofa large number ofrelatively small diamond particles on all surfaces which are intended toengage and dress a grinding wheel. All three of the dresser units areconsidered rotary dressers in the sense that they include means forrotating the shaped heads while in contact with a grinding wheel toeffect a dressing operation. The two dresser units 112 and 114 whichfunction to dress inner and outer sidewall portions ofa grinding wheelare rotated by a common motor means 118. The third dresser unit 116 isrotated by its own motor means 120 so that it can be controlledseparately from the pair of dresser units which dress the sidewalls of agrinding wheel. The three dresser units are rotated at relatively highspeeds (for example, at approximately 5000 r.p.m. or 3700 feet perminute) to effect a dressing operation. While the three dressing unitsare in contact with the grinding wheel 100, the grinding wheel is alsorotated. In a rough dressing operation, the grinding wheel may berotated at a relatively slow rate (for example, 5 rpm.) and in adirection which moves its sidewall surfaces in the same direction assurface movements of the two dresser units 112 and 114. When it isdesired to change the characteristic of dressing of the grinding wheel,the dresser units 112 and 114 may be reversed in their directions ofrotation so that hey are opposing the surface movement of the grindingwh :el 100 between them. Such a change in dressing operation may bedesired in a finish dressing process wherein the grindii g wheel isrotated at a much higher rate (for example, at 2000 r.p.m. or 60007000feet per minute). FIG. 3 shows the movement of the grinding wheel 100between the dresser units 112 and 114 in a direction which is the sameas the surface movements of the two dresser units. If it is desired tochange the dressing characteristic, the grinding wheel is rotated in thesame direction as shown in FIG. 3, but the two dresser units 112 and 114are reversed in their rotations. Also, dressing characteristics can bechanged by providing variable speed motors for the rotary dresser unitsso that the rotation of the units can be varied over a range ofsurfacespeeds.

FIGS. 2 through 4 illustrate basic adjustment means which are providedfor the dresser units, especially the two dresser units 112 and 114which contact inner and outer sidewalls of the cup-shaped grinding wheel100. As is well-known in this art, it is very important to carefullycontrol the precise shape and size ofa grinding wheel so as to effect aprecision cut in a workpiece. To a large extent, the shape of thegrinding wheel can be controlled by the shapes of the dresser headswhich contact the grinding wheel, but in addition, it is necessary to beable to provide for some modification or adjustment of whatever shapemay be imparted to the grinding wheel by a particular set of rotarydressers. This is especially critical with respect to the sidewallportions ofthe grinding wheel since the sidewall portions include almostall of the grinding area which will contact a workpiece, and therefore,the sidewall dresser units of this invention are provided with a numberof adjustment features for controlling precise positions of the twodresser units 112 and 114.

Considering only the two dresser units 112 and 114. as illus trated inFIGS. 2 and 3, it can be seen that the two units are mounted relative tothe grinding wheel, during a dressing operation, so that their axes ofrotation 122 and 123, respectively, are parallel to each other and tothe axis of rotation 126 of the grinding wheel. In addition, as shown inFIG. 3, the axes of rotation 122 an 124 lie on a line 128 whichcomprises an extension of a single radius of the grinding wheel. Usingthese relationships as references, there is an imaginary apex point ofthe grinding wheel at 130 (see FIG. 2), and this apex reference mayserve as a guide for positioning the third dresser unit 16 relative tothe end of the cup-shaped grinding wheel. For example, in a typicaldressing setup, the third dresser unit 116 is positioned to make contactwith the grinding wheel at a level which is just above (0.010 inches,for example) the position of the imaginary apex" so that there willalways be some dressing of the very end of the grinding wheel. Thevarious adjustment features which are provided for the dresser units,especially the two units 112 and 114, are concerned with providingvariations in the positions of the two dresser units relative to eachother and to the grinding wheel itself.

The adjustment features for the side dressers 112 and 114 include thefollowing:

a. A first adjustment means for adjusting the spacing between the axes122 and 124 of the first and second dresser units 112 and 114. Thisadjustment means may comprise means for mounting the dresser unit 112for sliding movements toward and away from a fixed position of dresserunit 114. Such a mounting arrangement is shown. in FIGS. 2 and 3 whereinthe dresser unit 112 is carried by a mounting block 132 which can slidetoward and away from the dresser unit 114 on a track or guiding meansprovided in a separate mounting block 134 which carries the dresser I14.Fastening devices 126, such as bolts, can be used to fix the position ofthe block 132 once a correct spacing is determined, and elongate slots138 are provided in the block 134 so that the bolts 136 can be loosenedand moved with the movement of the block 132. This adjustment featureprovides for a variation in the point width of the lowermost annular endof the cup-shaped grinding wheel which is illustrated.

b. A second adjustment means for simultaneously moving both dresserunits 112 and 114 up or down the sidewalls of the cup-shaped grindingwheel so as to change the height at which a work tooth chamferingsurface is formed on each sidewall of the grinding wheel, as related tothe annular end of the grinding wheel. Both dresser units 112 and 114can be lifted and lowered as a unit by loosening fastening bolts 140 andsliding the mounting block 134 up and down on a track or guiding means142 associated with a separate mounting block 143 which carries themotor 118. Although not shown clearly in FIG. 2, the shaped heads of thedresser units 112 and 114 include somewhat irregular configurationswhich provide a surface on each sidewall of the grinding wheel, whichsimultaneously grinds a tooth profile and a chamfered top edge on atooth. This adjustment feature allows the level of chamfering to bechanged relative to the end of the grinding wheel.

c. A third adjustment means for simultaneously moving both of thedresser units 112 and 1141 along the radius line 128 so as to adjust thepositions of the dressers for various diameters of grinding wheels or tomodify the radial position of the annular end of the grinding wheel.This adjustment is provided by sliding a block member 144 back and forthon a mounting casing structure 146. The block member 144 carries allsubassembly components of the two dresser units 112 and 114 andtherefore, the two dresser units are simultaneously moved back and forthalong the radius line 128 when the fastening bolts 147 are loosened topermit a sliding movement of the block 144 in tracks or guide slots 148of the mounting casing structure I46. Relatively large adjustments mayhe provided for this movement so that the dresser structures can bepositioned to dress a wide range of diameters of grinding wheels. Forexample, it is contemplated that the illustrated dresser units may beadjusted to dress grinding wheels which vary in size from approximately9 inches in diameter to approximately 24 inches in diameter.

d. A fourth adjustment means for simultaneously tilting both of thedresser units 112 and 114 in the plane which passes through the radiusline 128 and both axes of rotation 122 and 124 of the dresser units. Inthe adjustment positions as illustrated in FIG. 2 this tilting movementwould take place about the imaginary apex point 130, and such movementhas the effect of changing the otherwise parallel relationship of theaxes of rotation of the two dresser units 112 and 114 relative to theaxis of rotation 126 of the grinding wheel. However, the real purpose inproviding this adjustment is one of changing the pressure angle which isformed on the sidewall surfaces of the grinding wheel (the pressureangle surface being the surface on a grinding wheel below the chamferedsurface mentioned above). This adjustment constitutes a very fine andcritical adjustment for carefully controlling the pressure angle of afinished toothed slot which is formed in a workpiece. The .adjustment ismade by loosening fastening bolts 150 so that a mounting block 152 t anslide and rotate relative to the fixed position of an ounting block 154.Curved tracks or guide slots 156 are j rovided to guide the tiltingmovements of the mounting block 152 and all of the components carried byit (the dresser units .112 and 114 and the motor 118).

. A fifth adjustment means for simultaneously tilting both of thedresser units 112 and 114 about an axis 158. The axis 158 passes throughthe axis of rotation 126 of the grinding wheel. Tilting movement of bothdresser units 112 and 114 about the axis 158 provides for a modificationof the profile of the sidewalls of the cup-shaped grinding wheel 100,and this modification, although slight, is important for precise controlof the tooth profile configuration. In accordance with known theoriesand techniques, the profile of a grinding wheel is modified to changethe bearing surface of a tooth which is formed by contact of thegrinding wheel with a workpiece. This ad justment is effected byloosening fastening bolts 160 and 162 so that the mounting blocks 132,134 and 143 can be rotated relative to an extended portion 164 of themounting block 152. It can be seen that the mounting block 143 isjournaled into the portion 164 of block 152 so that rotation takes placeabout the axis 158.

f. A sixth adustment means for lifting and lowering the level i of theaxis 158 so as to change the position of the point about which theabove-mentioned fourth and fifth adjustments can take place. Thisadjustment feature has the effect of changing the level from which theprofile adjustment is made on the sidewall surfaces ofa grinding wheel,for example, to make the profile modification symmetrical about a linerepresenting the mean height of a tooth. This adjustment is accomplishedby loosening fasteners 168 so that the mounting block 154 can be liftedand lowered on a track 170 relative to the slide block 144. The thirddresser unit 116 does not require the same number of critical adjustmentfeatures as discussed above for the sidewall dresser units 112 and 114.Therefore, the third dresser unit 116 may be mounted in a relativelyfixed position so as toalways contact the grinding wheel at or near theimaginary apex point 130. However, adjustment is provided for the thirddresser unit 116 to precisely set its position relative to the apex"point 130 (or to any other datum line which may be established for theoperation of the grinding machine), and an additional adjustment featuremay be provided lor automatically lifting the third dresser unit 116 bya sufficient amount to completely remove the grinding edge which isotherwise formed at the annular end of a cup-shaped grinding wheel. Suchan adjustment feature may be provided when it is intended to use thegrinding wheel in finish grinding operations where no contact is made bythe annular ind of the wheel with a previously roughed bottom of a toothslot.

FIGS. 5 through 13 illustrate details of a specific embodiment for thepair of dresser units 112 and 114 discussed above. The basicrelationships and adjustments which were discussed above with referenceto FIGS. 2 through 4 apply to the specific embodiment which will now bediscussed, and it is to be understood that this specific embodimentrepresents only one example of a detailed construction which can bemanufactured in accordance with this invention. Other examples ofconstruction, including equivalent variations, will come to mind tothose skilled in this art, and it is not intended that the presentinvention be limited to the specific example shown in FIGS. 5 through13.

FIGS. 5 and 6 illustrate two different perspective views of the dresserunits of this invention, as installed on a machine of the type shown inFIG. 1. Although the following discussion will emphasize the detailedfeatures of the pair of dressers 112 and 114, it can be seen that therelationship of the third dresser unit 116 is also shown in FIGS. 5 and6. As discussed above, all three dresser units are carried by arelatively large mounting casing structure 146, and this mounting casingstructure functions to properly position all dresser units relative toeach other and relative to a grinding wheel carried by the machine. Themounting casing structure 146 is pivotally attached at 108 to a portionof the machine, and a hydraulic ram functions to swing the entire casingstructure, and the dresser units mounted thereon, about the pivot 108 soas to place the dresser units into an operative position for dressing acup-shaped grinding wheel which is moved downwardly into engagement withthe rotary dresser heads. FIGS. 5 and 6 illustrate the dresser units insuch an operative position, and FIG. 5 clearly shows the upwardlydirected dressing heads of the two dressers 112 and 114 and ahorizontally disposed dresser unit 116. The shaped dressing headscontact opposite sidewalls and an annular end wall of the cup-shapedgrinding wheel when the grinding wheel is brought down into dressingengagement with the dresser units. However, it is to be un derstood thatdressing could be accomplished by moving all three dresser unitsupwardly into engagement with the grind ing wheel as well.

' FIG. 5 shows the mounting block 132 which carries the rotary dresser112 for movement towards and away from the second rotary dresser 114. Anadjustment device 232 is carried by the mounting block 134 so thatprecise movements of the dresser 112 can be made relative to theposition of the dresser 114. The adjustment means 232 includes athreaded member which can be manually turned to effect sliding move mentof the block 132 relative to the block 134, and this adjustment meanswill be discussed in greater detail with reference to FIGS. and 10. FIG.5 also illustrates the relationship of mounting block 134 relative tothe separate mounting block 143. The mounting block 134 can be movedvertically relative to the block 143, and this provides for the secondadjustment feature discussed above under (b). An electric motor 118 isshown as being mounted on the mounting block 143 for driving a pulley180. Both of the dressers 112 and 114 are driven from this motor 118,and the motor is preferably of a reversible type so that the directionsof rotation of the dresser heads can be reversed.

FIG. 6 illustrates the mounting block arrangements which provide for theadditional adjustment features discussed above, and the various slidingblocks and other members can be picked out by the reference numeralswhich are related to the discussion of what is shown schematically inFIGS. 2 and 3. Also, FIG. 6 shows a rear end portion 182 of the thirddresser unit 116, and it can be seen that the third dresser unit ismounted in the same mounting casing structure 146 which carries the twoside dresser units 112 and 114.

FIGS. 7 and 8 show the assemblies for the two dresser units 112 and 114of FIGS. 5 and 6, but the assemblies have been tilted and partiallyexploded to show detail. The views of FIGS. 7 and 8 are more or lessfrom the bottom of the dresser units, as compared to the positions inFIGS. 5 and 6, and the driving arrangement for the two dresser units 112and 114 is

1. In apparatus for dressing grinding wheels, especially cupshapedgrinding wheels, the improved combination comprising: first and secondrotary dresser units which function as a pair of dressers forsimultaneously dressing inner and outer sidewall portions of acup-shaped grinding wheel, said first and second rotary dresser unitshaving axes of rotation which are parallel to each other and to the axisof rotation of said cup-shaped grinding wheel when the dressers are indressing contact with the grinding wheel, mounting means for positioningsaid first and second rotary dressers into dressing contact with saidcup-shaped grinding wheel with the axes of rotation of both of thedressers being on a common radius line taken from the center of rotationof the grinding wheel, adjustment means for adjusting the positions ofsaid first and second dressers relative to each other and to saidgrinding wheel, and motor means for rotating said rotary dresser units.2. The combination of claim 1 wherein said adjustment means furthercomprises (a) a first adjustment means for adjusting the spacing betweenthe axes of rotation of said first and second dressers so as to changethe point width of the dressers relative to the grinding wheel, (b) asecond adjustment means for simultaneously moving both of said dressersup or down the sidewalls of said cup-shaped grinding wheel so as tochange the heights of chamfered surfaces on the sidewall portions of thegrinding wheel relative to annular end of the grinding wheel, (c) athird adjustment means for simultaneously moving both of said dressersalong said common radius line so as to adjust the positions of thedressers for various diameters of grinding wheels, (d) a fourthadjustment means for simultaneously tilting both of said dressers in aplane which passes through their axes of rotation and through the axisof rotation of said grinding wheel, so as to change the pressure anglecontact of said dressers with said grinding wheel, (e) a fifthadjustment means for simultaneously tilting both of said dressers in aplane at right angles to the plane in which said fourth adjustment meansis made so as to modify the profile of the inside sidewall of saidgrinding wheel, and (f) a sixth adjustment means for moving the level atwhich said fourth and fifth adjustment means take place.
 3. Thecombination of claim 1 wherein each of said first and second dresserunits includes a shaped head portion covered with diamonds for makingdressing contact with a grinding wheel.
 4. The combination of claim 1wherein said motor means comprises a reversible motor, whereby therotating contact of said dressers with a grinding wheel can be reversedto obtain different dressing characteristics.
 5. The Combination ofclaim 1 and including a third rotary dresser unit for dressing anannular end of a cup-shaped grinding wheel.
 6. The combination of claim5 wherein said third dresser unit is mounted relative to said first andsecond dresser units with its axis of rotation parallel to a radius linefrom the center of said grinding wheel and angularly displaced from saidcommon radius line along which said first and second dresser units arelocated during dressing operations.
 7. The combination of claim 6wherein said third dresser unit is angularly displaced from said commonradius line by 36*.
 8. The combination of claim 5 wherein said thirddresser unit includes means for moving said dresser unit towards theannular edge of said grinding wheel so as to remove an excess amount ofmaterial from the annular edge for certain grinding operations.
 9. Inapparatus for dressing grinding wheels, especially cup-shaped grindingwheels, the improved combination comprising: first and second rotarydresser units which function as a pair of dressers for simultaneouslydressing inner and outer sidewall portions of a cup-shaped grindingwheel, said first and second rotary dresser units having axes ofrotation which are parallel to each other and to the axis of rotation ofsaid cup-shaped grinding wheel when the dressers are in dressing contactwith the grinding wheel, a third rotary dresser unit which functions todress an annular end of said grinding wheel, means for moving all threerotary dresser units into and out of dressing engagement with a rotatinggrinding wheel, motor means for driving all three rotary dresser units.10. The improved combination of claim 9 and including adjustment meansfor adjusting the positions of said first and second rotary dressersrelative to each other and to said grinding wheel.
 11. The improvedcombination of claim 9 and including means for effecting relativemovement between said dresser units and said grinding wheel so as togenerate grooves in the sidewalls and the annular end of said grinding.12. The improved combination of claim 9 wherein said third dresser unithas an axis of rotation which is parallel to a radius of said grindingwheel and angularly displaced from another radius of said grinding wheelalong which said first and second dressers are positioned.
 13. Theimproved combination of claim 12 wherein said third dresser unit isangularly displaced from said first and second dresser units by anangular amount which divides a 360* circle into equal segments.
 14. Theimproved combination of claim 9 wherein said adjustment means furthercomprises (a) a first adjustment means for adjusting the spacing betweenthe axes of rotation of said first and second dressers so as to changethe point width of the dressers relative to the grinding wheel, (b) asecond adjustment means for simultaneously moving both of said dressersup or down the sidewalls of said cup-shaped grinding wheel so as tochange the heights of chamfered surfaces on the sidewall portions of thegrinding wheel relative to an annular end of the grinding wheel, (c) athird adjustment means for simultaneously moving both of said dressersalong said common radius line so as to adjust the positions of thedressers for various diameters of grinding wheels, (d) a fourthadjustment means for simultaneously tilting both of said dressers in aplane which passes through their axes of rotation and through the axisof rotation of said grinding wheel, so as to change the pressure anglecontact of said dressers with said grinding wheel, (e) a fifthadjustment means for simultaneously tilting both of said dressers in aplane at right angles to the plane in which said fourth adjustment meansis made so as to modify the profile of the inside wall of said grindingwheel, and (f) a sixth adjustment means for moving the level at whichsaid fourth and fifth adjustment means take place.
 15. The combinatioNof claim 9 wherein each of said dresser units includes a shaped headportion covered with diamonds for making dressing contact with agrinding wheel.
 16. The combination of claim 9 wherein the motor meansfor at least said first and second dresser units is a common motor forboth units.
 17. The combination of claim 16 wherein said motor means isreversible.